An AKB system compensates for changes in the cutoff voltage of a kinescope (or cathode ray tube) due to temperature, for example, during warm-up, and aging. The compensation is accomplished by inserting small offset currents into the kinescope driver circuits of each of the color channels to effectively change the respective cathode bias voltages. The magnitudes of the offset currents are varied according to cutoff measurements made during respective lines of the vertical blanking period of every field.
It is desirable to provide an AKB arrangement which may be embodied in an integrated circuit (IC), and which may be capable of being used in various television systems having different configurations. It is also desirable that such AKB IC be capable of being added as an optional feature to a television system without significant changes to its basic architecture. More specifically, it is desirable to provide an AKB IC which is capable of being used in a television system which includes a bias network which affects the kinescope bias from being cutoff while the AKB measurements are being made, as well as in a television system which does not contain such a bias network.